Urea, an organic compound, has two amine groups along with a carbonyl functional group. It metabolizes the nitrogen compounds in animals and is the main source of nitrogen in the urine of mammals. Urea is a colorless, odorless solid which is neither acidic nor basic. It is highly soluble in water. It is used as a fertilizer as the source of Nitrogen. The original production of urea was from the reaction between silver isocyanate and ammonium chloride:AgNCO+NH4Cl→(NH2)2CO+AgCl.
Urea is widely used as a fertilizer and it is believed that more than 80% of the world's urea production is used as a fertilizer. It has the highest nitrogen content (46%) of all solid nitrogen based fertilizers used. Urea in the soil is converted to ammonia by hydrolysis. The ammonia is then oxidized to nitrates by the bacteria present in the soil. The nitrates are the absorbed by the plants for its nutrients. Urea is also used as a base for the manufacture of many other nitrogen based fertilizers.
Commercially, urea granules are used over the regular prills since granules have smaller particle size distribution. This is a major advantage for mechanical application. Nano-granules of urea will have better mechanical application because the particle size is even narrower than the granules and a positive charge can be imparted to the particles to form an ionic bond with most soils which are negatively charged.
Urea decomposes into biuret which is very harmful for plant growth. Biuret is a very common impurity of urea. Biuret formation can occur when urea is subjected to heat above its melting point. The biuret content should be minimized to less than 3 mole percent in urea.
Urea is generally applied to the farms at intervals to minimize leaching losses. Urea loss due to volatilization can be minimized by adding it either during or before rains.
Currently, only 20-30% of N/P/K fertilizers reach the soil and then plant roots and get fixed. This causes the rest of the fertilizers to be washed away and results in eutrophication. This involves high usage of fertilizers and less grain yield. The potential to produce 2-3 times more than is currently possible is lost due to the several reasons explained above.
There exists a need for urea particles with improved properties for fertilizer applications as well as more economical and efficient methods of making urea particles.